BY JUSTIN RAYDecember 6, 2000 -- Follow the countdown and launch of a classified National Reconnaissance Office payload aboard a Lockheed Martin Atlas 2AS rocket. Reload this page for the very latest on the mission.

WEDNESDAY, DECEMBER 6, 20000600 GMT (1:00 a.m. EST)
A satellite cargo hidden in a veil of secrecy was successfully transported into space by a Lockheed Martin Atlas 2AS rocket on Tuesday evening during a widely watched launch from Florida's Cape Canaveral. Read our full story.

0320 GMT (10:20 p.m. EST, Tues.)
Lockheed Martin has announced data on the orbit achieved during the launch, and the Atlas rocket performed right as expected. The classified NRO payload was placed into a geosynchronous transfer orbit around Earth with an apogee of 20,241 nautical miles of the planned 20,252 miles, a perigee of 145.95 nautical miles of planned 145.99 miles and inclination of 26.5 degrees.

0317 GMT (10:17 p.m. EST)
T+plus 30 minutes. SPACECRAFT SEPARATION! A classified satellite payload for the U.S. National Reconnaissance Office has been released into space following a smooth launch tonight by the Lockheed Martin Atlas 2AS rocket. This marks the 54th consecutive successful launch by an Atlas rocket dating back to 1993.

0315 GMT (10:15 p.m. EST)
T+plus 28 minutes. Spinup of the Centaur upper stage has started in advance of payload deployment in less than two minutes.

0314 GMT (10:14 p.m. EST)
T+plus 27 minutes. The Centaur is beginning its reorientation maneuver to prepare for releasing the payload. The achieved orbit from the second Centaur burn is reported nominal.

0313 GMT (10:13 p.m. EST)
T+plus 26 minutes. MECO 2. Centaur has completed its second firing, completed the powered phase of today's launch. This was a guidance-commanded engine shutdown. Coming up on deployment of the NRO satellite at T+plus 29 minutes, 36 seconds.

0311 GMT (10:11 p.m. EST)
T+plus 24 minutes, 20 seconds. Centaur is up and burning again. The two RL-10 engines have reignited for a 91-second firing to accelerate the NRO payload into its required orbit around Earth.

0310 GMT (10:10 p.m. EST)
T+plus 23 minutes, 30 seconds. Small thrusters on the stage are firing to settle the propellant inside the vehicle's tanks to prepare for engine ignition.

0310 GMT (10:10 p.m. EST)
T+plus 23 minutes. The Centaur has started a sequence to prepare for engine restart, which is about a minute away.

0309 GMT (10:09 p.m. EST)
T+plus 22 minutes. Clean telemetry data from the rocket is being sent through a NASA Tracking and Data Relay Satellite.

0305 GMT (10:05 p.m. EST)
T+plus 18 minutes. The vehicle is now approaching the African Ivory Coast as it coasts above the Central Atlantic. A clean flight of the rocket continues.

0303 GMT (10:03 p.m. EST)
T+plus 16 minutes. Small thrusters on the Centaur stage are firing as necessary to keep the vehicle stable. About eight minutes away from Centaur restart.

0301 GMT (10:01 p.m. EST)
T+plus 14 minutes. The current orbit is 449 miles high, 94.9 miles on the low end and 28.169 degrees.

0259 GMT (9:59 p.m. EST)
T+plus 12 minutes, 20 seconds. The parking orbit achieved by the Atlas-Centaur vehicle is reported to be perfect. The perigee is within a tenth of mile of prediction, the apogee is within 200-hundreds of a mile of planned and inclination is right on the money to three decimal places.

0258 GMT (9:58 p.m. EST)
T+plus 11 minutes. Centaur and attached spacecraft are now in a coast period that will last 14.5 minutes in duration with restart of the twin engines expected at 24 minuutes, 18 seconds into flight.

0257 GMT (9:57 p.m. EST)
T+plus 10 minutes. MECO 1. The Centaur main engines have cut off as planned following the first of two planned firings to deliver the classified NRO payload into geosynchronous transfer orbit. So far all has gone as planned with no problems reported.

0256 GMT (9:56 p.m. EST)
T+plus 9 minutes. Everything is nominal. That is the report from the telemetry lab were live data coming back from the rocket is being examined.

0255 GMT (9:55 p.m. EST)
T+plus 8 minutes. Less than two minutes left in the Centaur stage's first burn.

0252 GMT (9:52 p.m. EST)
T+plus 5 minutes, 28 seconds. The sustainer engine on Atlas has shut down as planned. Separation of the Atlas stage confirmed and ignition of Centaur's two engines has occurred. Full thrust reported for the Centaur's RL-10 powerplants.

0250 GMT (9:50 p.m. EST)
T+plus 3 minutes. The booster engines have shut down and the booster package -- the bottom section of the rocket -- has been jettisoned. The sustainer engine of the Atlas vehicle still firing.

0247 GMT (9:47 p.m. EST)
LIFTOFF! Liftoff of the Lockheed Martin Atlas-Centaur 157 rocket with a National Reconnaissance Office satellite cargo cloaked in secrecy. And the vehicle has cleared the tower.

Shortly, the rocket's inadventant separation destruct safety system will be armed, the Centaur upper stage will go to internal power and the flight termination system will be armed.

0244 GMT (9:44 p.m. EST)
T-minus 3 minutes. The water system is being readied for activation at launch pad 36A. Water will flood the pad to suppress the sound produced at liftoff and protect the ground support systems.

0243 GMT (9:43 p.m. EST)
T-minus 4 minutes. The Atlas booster stage and Flight Termination System are switching from ground-supplied power to internal bateries. The ground trickle charge to the satellite payload has been stopped and the spacecraft is on internal power.

0242 GMT (9:42 p.m. EST)
T-minus 5 minutes and counting! The countdown has finally resumed for launch of the Lockheed Martin Atlas 2AS rocket with what is believed to be a data relay satellite for the National Reconnaissance Office from pad 36A at Cape Canaveral Air Force Station in Florida. There are now no problems standing in the way of liftoff at 9:47 p.m. EST.

0140 GMT (9:40 p.m. EST)
The Lockheed Martin final readiness poll of the entire launch team was just performed by Launch Conductor John Martin in the Complex 36 Blockhouse with all parties reporting a "go" for liftoff. Lockheed Martin Launch Director Adrian Laffitte then gave his approval for liftoff from the Mission Directors Center in the Cape Canaveral Industrial Area. The final Launch Decision Authority is in the hands of Col. Stephen Wojcicki, director of the NRO's Office of Space Launch and mission director for this flight. There were no problems reported and the "go" was given to resume the countdown at 9:42 p.m. EST for liftoff at 9:47 p.m. EST (0247 GMT).

0238 GMT (9:38 p.m. EST)
The upper level wind data has been loaded aboard the rocket. Also, the spacecraft team reports it is "go" for launch of the classified NRO payload tonight at 9:47 p.m. EST.

0237 GMT (9:37 p.m. EST)
The launch team was just informed that the readiness poll will occur in two minutes.

0232 GMT (9:32 p.m. EST)
Now 15 minutes from the planned launch time. All of the earlier problems appear to be resolved with the Atlas rocket finally nearing liftoff tonight.

There will be a readiness poll of the launch team and senior managers upcoming at 9:39 p.m. EST. If there are no problems, countdown clocks are due to resume from the T-minus 5 minute mark at 9:42 p.m. for liftoff at 9:47 p.m. EST from pad 36A at Cape Canaveral Air Force Station in Florida.

0229 GMT (9:29 p.m. EST)
The latest weather balloon data and guidance control program has been received from the Lockheed Martin team in Denver. It will take about 12 minutes to load that program into the vehicle, officials report.

The gyro unit temperature issue has been resolved and the Range is now "go" for launch. Liftoff remains targeted for 9:47 p.m. EST (0247 GMT).

0226 GMT (9:26 p.m. EST)
The one boat has moved clear of the launch danger box in the Atlantic. However, the Range remains "no go" while a sweep the area is performed by helicopters to ensure there are no other boats or aircraft in the zone.

0224 GMT (9:24 p.m. EST)
Officials have approved the plan to warm up the area around the gyro unit to increase its temperature. The Anomaly Team recommends disabling the computer-monitored operational temperature constraint on the unit and a launch team member to manually watch the limit of 7 degrees F.

0212 GMT (9:12 p.m. EST)
The upper level winds have now become a factor tonight. Engineers working with the wind data are waiting for more data from the latest weather balloon. Once the further data is received and computed to generate the rocket's flight profile, a guidance program will be created and loaded into Atlas' control computer. That work will likely push liftoff beyond 9:30 p.m. EST.

Weather balloons are released periodically throughout the countdown to collect wind speed and direction information in the atmosphere. That information is used to create the guidance program so the rocket knows what wind conditions to expect during flight.

0207 GMT (9:07 p.m. EST)
There is currently a boat in the restricted launch danger area in the Atlantic Ocean. The boat had been waiting to pass through the danger box until after launch. However, with this extended delay the Range has allowed the boat to proceed now. It is expected to be cleared by the new 9:30 p.m. EST (0230 GMT) liftoff time.

0203 GMT (9:03 p.m. EST)
The recommendation from the Anomaly Team is to increase the temperature in the area around the gyro unit that is currently cold. That extra heat should warm up the unit, which has hit its lower operational limit.

0200 GMT (9:00 p.m. EST)
ANOTHER NEW LAUNCH TIME! Engineers troubleshooting the rocket's RGU No. 1 continues. With that issue being worked and Range clearance being factored in, officials are now targeting liftoff for 9:30 p.m. EST.

0156 GMT (8:56 p.m. EST)
Tonight's available launch window extends to 10:12 p.m. EST. Officials are currently shooting for liftoff at 9:10 p.m. EST if the temperature concern with one of the rocket's gyroscope units can be resolved in time.

0152 GMT (8:52 p.m. EST)
NEW LAUNCH TIME! The troubleshooting with the heaters of a gyro unit in the rocket's guidance system continues. So countdown clocks will be held for an additional 10 minutes. Liftoff is now set for no sooner than 9:10 p.m. EST (0210 GMT).

0146 GMT (8:46 p.m. EST)
ANOTHER NEW TIME! The hold at T-minus 5 minutes is being extended five more minutes for liftoff so sooner than 9:00 p.m. EST. The Anomaly Team is looking at the temperature of the rocket's Rate Gyro Unit No. 1 again, which has hit its lower operational limit.

0142 GMT (8:42 p.m. EST)
The final readiness polls will be reperformed in about five minutes to ensure all systems are "go" to pick up the countdown for liftoff at 8:55 p.m. EST. The Range is now clear for launch.

0138 GMT (8:38 p.m. EST)
The Range reports it will be ready to support liftoff at 8:55 p.m. EST.

0137 GMT (8:37 p.m. EST)
The Anomaly Team reports that the low temperature measurement in the rocket's thrust section is not a problem and recommends continuing with the launch as-is.

0135 GMT (8:35 p.m. EST)
ANOTHER NEW LAUNCH TIME! The countdown will remain holding for 10 more minutes. Liftoff is now 8:55 p.m. EST (0155 GMT) at the earliest. The spacecraft ground station issue has been resolved. However, the Air Force-run Range is now "no go" some unknown reason at the moment.

0130 GMT (8:30 p.m. EST)
There is some optimism being reported that the fix to an air conditioning system at a satellite ground station may soon be in place. That would permit the countdown to resume and head for liftoff of the Atlas 2AS rocket from Cape Canaveral tonight. The countdown is currently holding at T-minus 5 minutes with a target liftoff time of no sooner than 8:45 p.m. EST (0145 GMT).

0126 GMT (8:26 p.m. EST)
NEW LAUNCH TIME! Again, the countdown remains holding at T-minus 5 minutes. The hold will be extended another 10 minutes. The launch has been pushed back to 8:45 p.m. EST at the earliest. The spacecraft team continues to work the ground station problem.

0121 GMT (8:21 p.m. EST)
The Anomaly Team is now looking at a temperature measurement in the rocket's thrust section.

0115 GMT (8:15 p.m. EST)
NEW LAUNCH TIME! The countdown will remain holding for another 10 minutes. Liftoff is now set for no sooner than 8:35 p.m. EST, pending resolution of the satellite's ground station issue.

0114 GMT (8:14 p.m. EST)
The Anomaly Team has suggested tweaking the temperature in the compartment around the Rate Gyro Unit No. 1 to correct the earlier concern noted below.

0111 GMT (8:11 p.m. EST)
A launch team member just reported the temperature on the rocket's Rate Gyro Unit No. 1 has been rising and is close the red-line limit. The RGU is part of the vehicle's guidance system.

0110 GMT (8:10 p.m. EST)
Besides the spacecraft constraint, there were no other problems being reported. The rocket and weather are "go" for liftoff.

0108 GMT (8:08 p.m. EST)
The Lockheed Martin final readiness poll of the entire launch team was just performed by Launch Conductor John Martin in the Complex 36 Blockhouse. The spacecraft ground issue was reported. Lockheed Martin Launch Director Adrian Laffitte has ordered this hold at T-minus 5 minutes be extended an extra 10 minutes. So liftoff is now set for no sooner than 8:25 p.m. EST.

0106 GMT (8:06 p.m. EST)
The countdown will not be resuming for liftoff at 8:15 p.m. EST. The spacecraft team reports an air conditioning unit at a ground facility has failed. So the launch will be put on hold while a portable air conditioning unit is brought in. Further details are not available given the classified nature of the payload.

Tonight's available launch window extends to 10:12 p.m. EST (0312 GMT). There is no estimation on a new liftoff time for tonight.

0104 GMT (8:04 p.m. EST)
The final readiness polls of the launch team members and the senior managers is upcoming in about three minutes. All parties will be polled to determine if there are any constraints to picking up the countdown at T-minus 5 minutes for liftoff at 8:15 p.m. EST tonight.

0100 GMT (8:00 p.m. EST)
Launch of the Atlas 2AS and its classified payload for the U.S. National Reconnaissance Office is now just 15 minutes away from Cape Canaveral Air Force Station in Florida. At launch the rocket will perform a roll maneuver and head eastward away from the Cape on its way to a geosynchronous transfer orbit. Release of the satellite to complete the launch will occur 29 minutes, 36 seconds after liftoff.

0054 GMT (7:54 p.m. EST)
T-minus 5 minutes and holding. The countdown has entered the planned hold. This pause is slated to last 16 minutes. There are no major technical problems being worked by the launch team and weather conditions are "go". This countdown has progressed extremely smoothly with virtually no problems addressed. The Atlas-Centaur rocket is now fully fueled and just awaiting the final minutes before liftoff at 8:15 p.m. EST.

0049 GMT (7:49 p.m. EST)
T-minus 10 minutes and counting. Coming up on the planned 16-minute built-in hold at T-minus 5 minutes, one minute longer than expected. The extra minute will synch up the countdown to the adjusted launch time of 8:15 p.m. EST. The liftoff was pushed back a minute to avoid sending the vehicle on a course that would pass too close to an object already in space.

0045 GMT (7:45 p.m. EST)
Now 30 minutes away from the scheduled launch time of the Atlas rocket.

0043 GMT (7:43 p.m. EST)
Launch Weather Officer Jim Sardonia reports all weather conditions are currently "go" and forecast to remain acceptable for liftoff at 8:15 p.m. EST (0115 GMT). There are no clouds or rainshowers anywhere near Cape Canaveral and the winds at pad 36A at from the northwest at 8 gusting to 14 knots -- well below the 24-knot limit. The upper level winds remain persistent, Sardonia reported with a maximum wind of 112 knots at 35,000 feet.

0038 GMT (7:38 p.m. EST)
The pogo suppression system at pad 36A is being readied. The system will be used to dampen the "bounce" of the rocket during engine ignition. The self test of the flight termination system has been completed. And the Atlas liquid oxygen tank has reached flight level.

0034 GMT (7:34 p.m. EST)
The final planned pre-launch weather briefing is scheduled for five minutes from now when we expect another update on the upper level winds.

Interrogation checks have been completed to verify the rocket's C-band beacon is ready for use to track the vehicle during flight.

0027 GMT (7:27 p.m. EST)
An inhibited self test of the rocket's Flight Termination System is starting. The FTS would be used to destroy the vehicle in the event of a malfunction during launch.

0025 GMT (7:25 p.m. EST)
The Atlas liquid oxygen tank has reached the 98 percent level. It will be topped off to flight level shortly.

0019 GMT (7:19 p.m. EST)
Fueling of the Atlas rocket and its Centaur upper stage goes on. The Centaur liquid oxygen tank is now full at flight level, the Atlas liquid oxygen tank is 90 percent full and increasing and the Centaur liquid hydrogen tank is just over the 80 percent level.

0015 GMT (7:15 p.m. EST)
Now inside the final 60 minutes of the countdown to launch of a Lockheed Martin Atlas 2AS rocket from Cape Canaveral Air Force Station at 8:15 p.m. EST, a time adjusted one minute based on the rocket's trajectory to avoid an orbiting object.

Our live reports are coming to you from a view area at Complex 41 where Lockheed Martin is building its launch control center for the next-generation Atlas 5 rocket.

The countdown is progress very smoothly tonight with no significant problems being discussed at present. The ground weather conditions are acceptable right now and forecast to remain that way for launch. The high altitude winds above 25,000 feet are being monitored closely, but those winds are currently within limits.

Fueling operations continue with the Atlas liquid oxygen tank 80 percent full and the Centaur liquid hydrogen tank at 50 percent. The Centaur liquid oyxgen tank is being topped off at flight level.

0005 GMT (7:05 p.m. EST)
The liquid hydrogen chilldown is now complete and the super-cold fuel is flowing to fill the Centaur upper stage. The cryogenic propellant will be consumed with liquid oxygen by the stage's Pratt & Whitney-made RL-10 engines to propel the classified NRO satellite cargo into a geosynchronous transfer orbit tonight.

Meanwhile, the Atlas liquid oxygen tank is now 40 percent full.

0000 GMT (7:00 p.m. EST)
The liquid oxygen tank inside the Atlas booster stage is now at 20 percent. The rocket's shiny exterior is now turning a frosty white as a thin layer of ice forms from the super-cold liquid oxygen.

Meanwhile, Centaur liquid oxygen topping to flight level has started. As the countdown proceeds, the tank will be replenished to replace the cryogenic liquid oxygen that naturally boils away.

TUESDAY, DECEMBER 5, 20002354 GMT (6:54 p.m. EST)
The final alignment of the Atlas rocket's inertial navigation guidance computer has been completed, and the flight control system final preps are now beginning.

2351 GMT (6:51 p.m. EST)
The Centaur liquid oxygen tank has reached 95 percent full level where it is being maintained. Topping to 100 percent will be completed later. And now loading of liquid oxygen into the Atlas booster stage is beginning.

2345 GMT (6:45 p.m. EST)
Now 90 minutes away from the adjusted liftoff time of 8:15 p.m. EST (0115 GMT). The one minute delay is due to a Mission Assurance COLA that ensure the rocket does not fly too close to an orbiting object already in space.

The chilldown conditioning of liquid hydrogen propellant lines at pad 36A is now starting. This process is like the one performed on the liquid oxygen side whereby a small amount of the liquid is released from the pad's storage tank to prepare the plumbing for transferring the Minus-423 degree F fuel into the rocket.

Loading of liquid oxygen into the Centaur upper stage continues with the tank having reached 70 percent full.

Also at this time the doors of the Complex 36 Blockhouse are being sealed. The 120-member launch team is inside the blockhouse controlling the countdown just a few hundred yards away from pad 36A.

2335 GMT (6:35 p.m. EST)
The Centaur upper stage's liquid oxygen tank is now 20 percent full in this early portion of fueling operations.

2333 GMT (6:33 p.m. EDT)
The Air Force has announced some Mission Assurance COLAs, or Collision Avoidance periods, for tonight's launch window, which will prohibit liftoff during several sections of the available 118-minute window. The window has been divided into four "launch opportunities" in which the rocket can launch tonight. They are:
-8:15 to 8:17 p.m. EST;
-8:19 to 9:10 p.m. EST;
-9:12 to 9:47 p.m. EST;
-9:49 to 10:12 p.m. EST

The result is the Atlas will not fly as planned at 8:14 p.m. EST, rather liftoff will delayed by one minute to 8:15 p.m. EST (0115 GMT). Should the launch slip later into the window for some reason, the four periods listed above are when the rocket is allowed to blast off.

2328 GMT (6:28 p.m. EDT)
Chilldown conditioning of the liquid oxygen transfer lines at pad 36A has been completed and the launch team is now beginning to fill the Centaur upper stage with its its supply of super-cold cryogenic oxidizer. The liquid oxygen is chilled to Minus-298 degrees F, and will be consumed by the Centaur's twin RL-10 engines along with liquid hydrogen to be pumped into the start a little later in the countdown.

2315 GMT (6:15 p.m. EST)
The "chilldown" procedure is now starting to thermally condition the liquid oxygen propellants lines at pad 36A in advance of loading the Centaur upper stage. Chilldown is a process in which a small amount of the super-cold liquid oxygen is released from the pad's storage tank into the feed lines that lead to the rocket.

Meanwhile, gaseous helium chilldown of the Centaur engines and pneumatic bottle charge for the stage have started. The latest steering program is being loaded into the rocket's guidance computer based upon the upper level wind conditions. Also, checks of the wind damper arm and launcher pyrovent arm connecting the Atlas 2AS rocket with the launch tower is underway.

2314 GMT (6:14 p.m. EST)
T-minus 105 minutes and counting. The countdown has been restarted after a planned half-hour built-in hold. Activities remain on track for liftoff in two hours at 8:14 p.m. EST (0114 GMT).

2310 GMT (6:10 p.m. EST)
Lockheed Martin Launch Conductor John Martin has just polled the launch team for a readiness to begin fueling the Atlas rocket. All parties reported "go" status. The Air Force, which is governing this launch, then polled with senior management for approval to start loading super-cold liquid propellants into the vehicle. Countdown clocks are due to resume at 6:14 p.m. EST from the T-minus 105 minute mark and the initial stages of fueling will get underway moments later.

2259 GMT (5:59 p.m. EST)
Now half-way through this 30-minute scheduled hold at T-minus 105 minutes. The launch team is not working any significant hardware issues and only upper level winds are a concern for liftoff tonight. At launch pad 36A, technicians are finishing up work securing the complex before departing so fueling of the rocket can get underway.

The Air Force reports there are no Safety Collision Avoidance periods, or COLAs, that would prohibit liftoff during any portion of tonight's 118-minute launch window. Mission Assurance COLAs are still to be determined. Also, computer analysis shows that should a explosion occur, debris would fall in the cleared impact areas based on current wind conditions tonight.

The count has 45 minutes of built-in holds scheduled over the course the day that will lead to liftoff. A second and final hold is planned at T-minus 5 minutes for 15 minutes. The holds are designed to give the launch team a window of time to work any problems that could arise without delaying other pre-flight preparations.

Retraction of the 219-foot tall mobile service tower has been completed with the structure now in the launch position. The tower is used to erect the rocket on the launch pad, provide access for workers to all areas of the vehicle and protection from the weather. It is electrically driven on four-wheel assemblies.

In the countdown, the C-band systems test has started. The beacon is used to track the rocket in flight. Also, monitoring of the hazarous gas detection system has begun and the high-flow rate helium purges have started for the Centaur upper stage.

2234 GMT (5:34 p.m. EST)
The first two weather balloons have revealed acceptable upper level wind conditions at the moment. Those balloons will continue to be released over the next three hours through launch. The strong winds are being caused by the jet stream, which is located just to the south of the Cape. Should the core of the jet stream move any further northward, the winds aloft will increase. Winds are currently topping out at 112 knots at 37,000 feet.

2214 GMT (5:14 p.m. EST)
The mobile service tower at launch pad 36A is beginning to roll away from the Atlas 2AS rocket. Also, the launch team is starting the final alignment of the vehicle's guidance computer following the completion of a navigation test.

Over the past couple of hours, the launch team at Complex 36 have worked through propulsion launch preps for the Atlas and Centaur stages, powered up the rocket's flight control system, conducted Atlas hydraulic system and Atlas and Centaur pneumatic preps and Centaur main engine igniter checks were also started.

2210 GMT (5:10 p.m. EST)
The problem with the signal strength coming from the classified NRO payload atop the Atlas rocket appears to have been resolved. The engineers troubleshooting the issue say there is no action required at the launch pad, that a backup communications route will be used and the spacecraft can now be put into its final launch configuration.

2159 GMT (4:59 p.m. EST)
MAN STATIONS FOR COUNTDOWN. The Integrated Launch Operations have begun for today's launch attempt for the Atlas rocket. The countdown is being controlled from the Complex 36 Blockhouse where the entire 120-member launch team has assembled to oversee the final three hours of the operations leading up to liftoff of AC-157.

The latest weather update from Launch Weather Officer Jim Sardonia indicates there is a severe upper level wind shear between 25,000 and 35,000 feet. Weather balloons are being released periodically to watch the trends in the winds and collect speed and direction information.

The winds increase steadily from the surface up to 25,000 feet, then jump dramatically to a max wind of 114 knots at 35,000 feet. Such a shear poses a threat to the rocket's ability to control itself during passage through that area of the atmosphere.

Ground level weather conditions are looking favorable with pad winds dropping as the sun sets. There is just a 20 percent chance surface winds will violate the limit of 24 knots.

2145 GMT (4:45 p.m. EST)
Good afternoon from Cape Canaveral Air Force Station where the final hours are ticking away for tonight's planned launch of a Lockheed Martin Atlas 2AS rocket to deliver a classified satellite payload into Earth orbit for the U.S. National Reconnaissance Office.

Launch of the Atlas-Centaur 157 vehicle remains on schedule for 8:14 p.m. EST (0114 GMT) from pad 36A at the Cape. Tonight's available launch window in which to get the rocket airborne extends for 118 minutes to 10:12 p.m. EST (0312 GMT).

A steady northerly wind on the ground and stiff upper level winds are somewhat of a concern currently for launch officials. Those winds will be monitored throughout the remainder of the countdown. Otherwise, the skies a crystal clear, visibility extends to the horizon and temperatures, although on the chilly side, are in the low-60s F. A full weather briefing is upcoming at 4:49 p.m. from Launch Weather Officer Jim Sardonia.

There is one technical problem being worked at this time. The Anomaly Team has been convened to discuss data dropouts with the secret NRO spacecraft payload. No further information is currently available.

2125 GMT (4:25 p.m. EST)
Activities are proceeding at Cape Canaveral for tonight's launch of the Atlas 2AS rocket for the National Reconnaissance Office. Liftoff remains targeted for 8:14 p.m. EST. At Complex 36, the launch team is preparing to begin the Integrated Launch Operations at 4:59 p.m. EST, which is the final phase of the countdown. Retraction of the mobile service tower from around the rocket follows 15 minutes later.

Our continuous live coverage of the countdown and live streaming Webcast begins at 4:50 p.m. EST.

1745 GMT (12:45 p.m. EST)
As launch time nears for today's scheduled blastoff of the Atlas rocket, officials are keeping a close eye on strong winds at both the surface and high altitudes.

The latest update from Air Force Launch Weather Officer Jim Sardonia is the earlier threats of unfavorable clouds and rainshowers won't be concerns for launch today. However, gusty winds at launch pad 36A and upper level wind conditions could be problematic. Here is Sardonia's forecast from 12 noon EST today:

"Concerns have shifted from coastal rainshowers and cumulus clouds to surface and upper-level winds. Surface winds will be gusty today as a strong pressure gradient remains over the Florida peninsula. Winds at SLC36 will remain high this afternoon, but are expected to decrease after sunset. An upper-level disturbance passing through the area has triggered scattered rainshowers off the coast over the Gulf Stream, however these showers are now expected to remain outside of 10 nautical miles from SLC 36.

"The upper-level winds this morning are showing an area of severe wind shear between 25,000 and 30,000 feet, with wind speeds increasing at a rate of 30 knots per thousand feet. Maximum winds aloft are expected to be ~ 120 knots at 35,000 feet.

"The main concerns today include the chance of peak winds at SLC 36 above the 24 knot launch constraint and strong upper-level winds."

The launch time forecast calls for a broken deck of cumulus clouds at 3,000 feet with five-eighths sky coverage, visibility of seven miles, north-northeasterly winds 15 gusting to 24 knots as measured at the 90-foot level of the launch pad tower, a temperature of 60 to 62 degrees, relative humidity of 80 percent and the chance of isolated coastal rainshowers.

Sardonia is giving an overall chance of violating the launch weather rules of 20 percent. Upper level winds, however, are not considered to be a launch weather issue but rather a rocket constraint. The winds are monitored with the use of weather balloons to ensure the conditions aloft are safe for the vehicle to fly through during flight. Winds can't be too strong or else they could force the vehicle off course or cause it to break apart.

1615 GMT (11:15 a.m. EST)
The Lockheed Martin Atlas-Centaur 157 rocket is nine hours away from its scheduled liftoff time today on a dedicated mission for the U.S. National Reconnaissance Office. Clocks are due to begin ticking down at 11:24 a.m. EST. Launch remains scheduled for 8:14 p.m. EST (0114 GMT) from pad 36A at Cape Canaveral Air Force Station in Florida.

MONDAY, DECEMBER 4, 20002330 GMT (6:30 p.m. EST)
A hush-hush spacecraft believed to be a new orbiting data relay station for the American fleet of spy satellites is poised for launch Tuesday evening atop a Lockheed Martin-built Atlas 2AS rocket from Cape Canaveral.

The launch was pushed back one day to give technicians time to study a problem with a rocket engine back in the factory that is similar to two installed aboard the Atlas on the launch pad.

Late last week during a routine acceptance test firing of a liquid hydrogen/liquid oxygen-fed RL-10 engine at maker Pratt & Whitney, the powerplant did not perform as expected. Data revealed shifts in thrust produced by the engine.

Further analysis over the weekend determined the thrust shifts were caused by the engine's thrust controller, a problem isolated to that particular component on that engine. Thrust controllers on the two RL-10 engines mounted to the Centaur upper stage of the Atlas rocket to fly Tuesday were checked out satisfactory during pre-flight tests.

With the last-minute double-checking completed, senior managers conducted final launch readiness meetings on Monday and approved plans for liftoff on Tuesday at 8:14 p.m. EST (0114 GMT), the opening of a 118-minute window extending to 10:12 p.m. EST (0312 GMT).

At Cape Canaveral Air Force Station's pad 36A on Monday, workers spent the day installing the Safe and Arm devices on the rocket, performing a navigation test of the vehicle's guidance computer and starting the efforts to close the protective payload fairing nose cone around the classified satellite cargo for flight.

Few details about what the rocket is carrying are officially known, except that the satellite was designed and will be operated by the U.S. National Reconnaissance Office and is supposed to be delivered into a geosynchronous transfer orbit by the Atlas booster.

Military space observers suspect the craft is probably a data-relaying satellite used to send imagery and other intelligence information collected by U.S. spy satellites back to Earth.

The satellite is thought to have been built by the former Hughes Space and Communications Company, now known as Boeing Satellite Systems.

Air Force meteorologists are calling for a 40 percent chance cumulus clouds and rainshowers will violate the rules governing allowable weather for liftoff during Tuesday night's launch opportunity.

"Surface winds will continue to be gusty today as a strong pressure gradient remains over the Florida peninsula. Conditions are deteriorating slightly for launch day as most computer models are now agreeing on developing a surface trough offshore on Tuesday. With onshore winds and an upper-level disturbance passing through to further destabilize the atmosphere, there will be a good chance of enhanced cumulus clouds and coastal rainshowers within 25 nautical miles of SLC 36 during the launch countdown.

"These showers are expected to be transitory and short-lived however. With the extended length of the launch window, weather is expected to provide enough opportunities for launch.

"The main concern on launch day is the chance of enhanced cumulus clouds and coastal rainshowers within 5 nautical miles of SLC 36."

Launch time conditions are predicted to include stratocumulus clouds scattered at 2,500 feet with three-eighths sky coverage, cumulus clouds broken at 3,000 feet with five-eighths sky coverage and broken cirrus clouds at 27,000 feet with five-eighths sky coverage, visibility of five miles, northeasterly winds 12 gusting to 20 knots, a temperature of 60 to 62 degrees F, relative humidity of 80 percent and isolated coastal rainshowers in the area.

Should the launch slip to Wednesday night for some reason, the weather is forecast to improve to just a 20 percent chance of cumulus clouds and rainshowers delaying the liftoff. Conditions improve even further on Thursday night with only a 10 percent chance of weather being "no go" for launch.

Activities on launch day will get underway at 11:24 a.m. EST (1624 GMT) when the clocks begin counting down to the planned liftoff time of 8:14 p.m. EST (0114 GMT) in the Complex 36 blockhouse.

Spaceflight Now will be your source for comprehensive live coverage of the launch, including a running commentary of the countdown on this page and a streaming video broadcast that will begin at 4:50 p.m. EST (2150 GMT). Our coverage will originate from the vantage point of Lockheed Martin's new Atlas 5 Space Operations Center -- a state-of-the-art facility under construction at Cape Canaveral's Complex 41. The ASOC will serve as the nerve-center for the next generation Atlas 5 rocket.

MONDAY, DECEMBER 4, 20001730 GMT (12:30 p.m. EST)
The flight constraint against the RL-10 upper stage engine used by the Lockheed Martin Atlas rocket has been lifted, clearing the way for a classified launch Tuesday evening of an Atlas 2AS vehicle carrying a cargo for the U.S. National Reconnaissance Office.

The weather forecast has deteriorated, however. Air Force Launch Weather Officer Jim Sardonia is now predicting a 40 percent chance of clouds and rainshowers could postpone the launch.

We will have a full report a little later today.

SATURDAY, DECEMBER 2, 2000
A Lockheed Martin Atlas 2AS rocket and its clandestine payload for the U.S. National Reconnaissance Office won't make their appointed launch date Monday because of concerns surrounding the liquid-fueled upper stage engine used by the $100 million booster.

Liftoff from pad 36A at Cape Canaveral Air Force Station in Florida has been pushed back to at least Tuesday night. The available window that evening extends nearly two hours from 8:14 to 10:12 p.m. EST (0114-0312 GMT on Wednesday).

The postponement was ordered after unexpected data was received during a factory test firing of a Pratt & Whitney RL-10 engine like the ones used by the Atlas rocket's Centaur upper stage.

"They saw some data that hasn't been seen before," Lockheed Martin Launch Director Adrian Laffitte said Friday during an interview.

It was decided late Friday to forego a Monday launch opportunity while further testing and analysis was performed over the weekend to understand what the Air Force called "anomalous data" from the test firing and to ensure the two RL-10 engines installed on the Centaur stage for this launch are free of any problems. Pratt & Whitney had been tentatively scheduled to perform another so-called "hot-fire" test on Friday night.

Officials are due to meet on Monday for senior-level reviews to decide whether to lift the flight constraint against the RL-10 engines and permit the Atlas vehicle to fly on Tuesday.

This launch is already running over eight months late after an undisclosed problem with the secret satellite payload forced the mission to be put on hold. The rocket had been assembled on the pad and was ready for a March 20 liftoff when the classified problem came up.

The rocket was destacked from the pad and placed in storage at Cape Canaveral while the satellite issue was resolved.

Military space experts believe this is a data relay spacecraft used to beam reconnaissance imagery and information from the NRO's fleet of spy satellites back to Earth.

Publically released information indicates the Atlas will deliver the craft into a geosynchronous transfer orbit with a low point, or perigee, or 146 nautical miles, a high point, or apogee, of 20,247 nautical miles with an inclination of 26.5 degrees to the equator.

This launch will employ the Minimum Residual Shutdown mission profile in which the Centaur engines will fire until all fuel is consumed. This will allow the payload to be injected into a highest-energy transfer orbit as possible, reducing the amount of velocity change the satellite will later have to perform. However, there is ceiling imposed on the Centaur of achieving an apogee no higher than 23,761 nautical miles.

The craft would later use its onboard kick motor to achieve a circular perch in geostationary orbit 22,300 miles above Earth.

The NRO previously released video and photographs of a communications relay satellite under construction at Hughes Space and Communications, which is now Boeing Satellite Systems.

The weather forecast for Tuesday night is generally favorable for launch with an 80 percent chance of acceptable conditions. Air Force Launch Weather Officer Jim Sardonia issued the following forecast on Saturday:

"The remnants of a weak cold front are expected to move through central Florida tonight increasing the cloud cover and bringing a very slight chance of a passing rainshower. Surface winds are expected to increase late Sunday and Monday as strong high pressure builds behind this front. On launch day, winds are expected to be northeasterly and moderate. With onshore winds, there will be a chance of a few enhanced cumulus clouds and coastal rainshowers within 25 nm of SLC 36 during the launch countdown. The main concern on launch day is the slight chance of coastal rainshowers within 5 nm of SLC 36."

The launch time conditions are predicted to include scattered cumulus clouds at 3,000 feet with three-eighths sky coverage, seven miles visibility or better, northeasterly winds 12 gusting to 20 knots, a temperature of 62 to 64 degrees, relative humidty of 80 percent and isolated coastal rainshowers in the area.

Should the launch slip to Wednesday night, there is again an 80 percent chance of good conditions. The concerns will continue to be enhanced cumulus clouds and coastal rainshowers.

When this launch does occur Spaceflight Now will provide extensive live coverage including a streaming Webcast and continuous status updates beginning with the start of the final countdown three hours and 15 minutes before blastoff.

Our reports and broadcast will originate in Lockheed Martin's new Atlas 5 Space Operations Center being built at Cape Canaveral's Complex 41. Nicknamed the ASOC, this facility will be the launch control center for the next-generation Atlas 5 rocket.

Photo gallerySpaceflight Now looks back to last Tuesday's flight of the Lockheed Martin Atlas 2AS rocket with a secret satellite cargo with a gallery of spectacular launch photographs.OPEN GALLERYVideo vault
The Lockheed Martin Atlas 2AS rocket lifts off from Cape Canaveral with a classified payload for the U.S. National Reconnaissance Office.PLAY (381k, 30sec QuickTime file)Flight data fileVehicle: Atlas 2AS (AC-157)Payload: Classified NROLaunch date: Dec. 5, 2000Launch window: 8:14-10:12 p.m. EST (0114-0312 GMT on 6th)Launch site: SLC-36A, Cape Canaveral, Fla.Pre-launch briefingLaunch timeline - Chart with times and descriptions of events to occur during the launch.Atlas 2AS vehicle data - Overview of the rocket that will launch the classified NRO payload.Ground track - See the trajectory the rocket will follow during its flight.Atlas index - A directory of our previous Atlas launch coverage.SnapshotThe special decal on the Atlas' nose cone. Learn more about the meaning of the "Great Bear" name given to this launch. Photo: NROInside the blockhouseStep inside the historic Complex 36 Blockhouse where the 120 members of the launch team control every countdown and liftoff of Atlas rockets from Cape Canaveral.VIEW (286k QuickTime file)Hubble PostersStunning posters featuring images from the Hubble Space Telescope and world-renowned astrophotographer David Malin are now available from the Astronomy Now Store.U.S. STOREU.K. & WORLDWIDE STOREGet e-mail updates
Sign up for our NewsAlert service and have the latest news in astronomy and space e-mailed direct to your desktop (privacy note: your e-mail address will not be used for any other purpose).
Enter your e-mail address:Shuttle calendarIn this 2001 calendar, John Sexton turns the space shuttle into an art form with his unique black and white photographs of the hardware.MORE - amazon.comMORE - amazon.co.ukRide a rocket!A 50-minute VHS video cassette from Spaceflight Now features spectacular "rocketcam" footage from April's launch of NASA's 2001 Mars Odyssey probe. Available from the Astronomy Now Store in NTSC format (North America and Japan) and PAL (UK, most of Europe, Australia and other countries).Station CalendarNEW! This beautiful 12" by 12" wall calendar features stunning images of the International Space Station and of the people, equipment, and space craft associated with it, as it takes shape day by day in orbit high above the Earth. U.S. STOREU.K. & WORLDWIDE STORE